Ch12: Early genetics and Mendel Advanced Biology Chapter 12

Research done by such people as Josef Koelreuter and T.A. Knight Early Genetics Research done by such people as Josef Koelreuter and T.A. Knight Hybridizations - the mating of unlike parents to produce an offspring

Early Genetics Segregation - after mating, traits segregate to either offspring. Some offspring show same trait as parent, some show different traits

True-Breeding - Varieties are uniform from generation to generation. Early Genetics True-Breeding - Varieties are uniform from generation to generation.

picked up where Knight left off, testing garden pea plants Mendel’s Work picked up where Knight left off, testing garden pea plants

Mendel’s Work Two ways to produce offspring Self-fertilization Or by doing an experimental cross- pollinate a plant using pollen from a different plant with alternative characteristics

Mendel’s Work Monohybrid cross: a cross to study only 2 variations of a single trait Mendel produced true-breeding pea strains for 7 different traits -each trait had 2 alternate forms (variations) -Mendel cross-fertilized the 2 true-breeding strains for each trait

What exactly did Mendel do? 1st- allowed plants to self-fertilize for many generations to ensure that each trait would be constant for each generation 2nd- Crossed purple plants with white plants 3rd- Allowed those plants to self-pollinate and record the results

What did Mendel find? Hybrid- The resulting generation from two different parents First Filial Generation F1 - Contains the hybrid generation - in Mendel’ case, all the flowers were purple.

What did Mendel find? Dominant Trait - the trait that is expressed - purple flowers Recessive Trait - the trait that is masked or not expressed

What did Mendel find? Second Filial Generation F2 - Contained the recessive trait not exhibited in the F1 - white flowers Mendelain Ratio - 3 parts dominant to 1 part recessive

1) Parents transmit information in the form of genes Mendel’s model: 5 parts 1) Parents transmit information in the form of genes

Mendel’s model: 5 parts 2) Each human contains two factors for a specific trait. These factors may code for the same form of the trait or code for an alternative form of that trait.(Diploid). During Meiosis, the forming of a haploid gamete, only one factor for each trait is included in the genome and that is random

3) Alleles - two of the same alleles = homozygous Mendel’s model: 5 parts 3) Alleles - two of the same alleles = homozygous two different alleles = heterozygous

Mendel’s model: 5 parts 4) Alleles are independent of each other. The only difference is which one is “turned on”

Mendel’s model: 5 parts 5) All genes are not expressed. Some are turned on and some are turned off. All the alleles an individual has is called genotype. The physical characteristics exhibited by an individual is called phenotype.

Mendel’s model: 5 parts Punnet Squares and the Test Cross (pg 240) - to test his work, Mendel used a punnet square to figure out how the alleles segregated.

Mendel’s Laws of Heredity Mendel’s first law of segregation - alleles segregate randomly Dihybrid – heterozygous for two genes

Mendel’s Laws of Heredity Mendel’s second law of Independent Assortment – genes on different chromosomes assort independently during meiosis